As is known, safety valves and default valves are generally used in civil or residential and industrial water and gas user installations. Another case in which these valves are used is represented for example by public installations where water is made available to the public, such as in greens, parks and the like. The purpose of safety valves is principally to enable the shut-off member to be fixed and maintained securely in a predetermined position, namely open, closed or an intermediate position. The position in which the shut-off member is set must if possible be maintained even if the valve control means is tampered with or vandalized, as often happens with public installations. The incorporation of a lock in the handle of such safety valves, having a ball shut-off member, for example, is therefore known.
Default valves, on the other hand, are usually used at the inlet of the above-mentioned user installations and their purpose is to enable the water or gas supply company to cut off the supply of water or gas, that is to say, to lock the valve shut-off member in the closed position, if payment has not been made for previous supplies or in other particular situations. The locking of the shut-off member in the closed position is usually done by means of a sealing wire whose ends are crimped into a lead seal, or by means of a padlock, or by a lock incorporated in the valve control handle, in the same way as with safety valves. To enable the sealing wire or padlock to be fitted, known valves include two eyelets for the sealing wire or the staple of the padlock, that is one eyelet in the valve body and the other eyelet in the shut-off member control means. Known safety and default valves have many disadvantages.
A sharp jerk or blow on the handle of a safety valve may break the lock bolt, open the shut-off member and cause an unauthorized release of water or gas. While such acts of vandalism carried out on, say, safety valves fitted to sprinkler installations in public parks may result in damages and unauthorized releases of water or even flooding, in the case of valves on gas pipes, e.g. in unfinished buildings, or in the case of valves situated close to meters installed on the outside of buildings, such vandalism may cause explosions and considerable damages to people and structures.
The acts of vandalism, tampering, and the cutting of the leaded or sealing wires and padlock staples in default valves can lead to an unauthorized release of water, or gas, with a consequent detriment of the supply company, where a new sealing wire as well as a new padlock can then easily be fitted by the user himself, as has been discovered in many cases.
Another problem common to known safety and default valves is that the valve control handles housing the lock, or comprising the abovementioned eyelets for the sealing wires and padlocks, must be made in a variety of different shapes and sizes. This requires an increased expenditure on production and the holding of stocks of these components.
British patent application GB 2,227,811 A discloses a ball valve with a control cap fitted with geometrical engagement and with a fixing screw on the control spindle of the shut-off ball. The cap terminates at the top with a tapered end with a recessed hexagon to take a hexagonal control key. A protective outer cap of plastic is fitted with a snap action over the control cap in such a way as to be rotatable. The protective cap has an opening on its top to allow direct access to said recessed hexagon in the control cap so as to control or turn the shut-off member. The purpose of the protective cap is to prevent the control cap from being rotated by acting on it circumferentially with a gripping tool. Quite apart from the ease with which said plastic protective cap can be tampered with, it actually allows normal operation or turning of the valve with an ordinary hexagonal key.
French patent FR 2,717,552 A discloses a safety valve having a protective cylindrical metal cap which locks onto the control spindle of the shut-off member and onto the valve body in such a way that it cannot be rotated because of its geometrical engagement with corresponding projections on the valve body. A lock is housed removably on the opposite end of said cap from the valve and its bolt means engages with locking abutments provided in the cap. If the lock is opened and removed from the cap, the cap allows access to the control spindle of the shut-off member, which can be controlled with an appropriate socket wrench. On the other hand, if the lock is fitted to the protective cap, such access is prevented and the valve is made secure.
This patent FR 2,717,552 A represents the closest prior art and is considered in the preamble of claim 1.
However, this kind of valve has many drawbacks. Structurally, the protective cap is formed by an outer sleeve and an inner skirt and by numerous other components, making it expensive to produce, on the one hand, and laborious to assemble, on the other. The necessary geometrical engagement between the protective cap and the valve body requires the preparation of many different caps according to the dimensions of whichever valve is used.
Functionally, the protective cap fastened to the valve greatly restricts access to the shut-off member turning spindle. This is aggravated by the fact that, in order to house the lock, the protective sleeve must necessarily project a considerable amount from the free end of said turning spindle. This poor access to the ball turning spindle is also unfavorable because said turning spindle can only be operated with a special key which must necessarily be inserted into the protective cap. This creates even greater difficulties if the safety valve is installed in underground manholes, making access somewhat difficult. Another disadvantage is that the rigidity of the cap relative to the valve body makes it possible to exert a force action onto the protective cap, for example with a gripping or lever type of tool.